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Old 05-16-2018, 5:46 PM
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Default SDS100 vs Motorola - DSP audio delay

Can anyone who has compared an SDS100 to a Motorola, advise how close the audio processing is between the two in P25 and analog? I run multiple scanners next to Motorola radios, and found that the delayed audio in the x36HP scanners resulted in a very noticeable echo effect. The Whistler WS/TRX match just about perfectly, s easier to understand what is being said when both receive the same transmission at the same time.

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Old 05-16-2018, 10:24 PM
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I had the opportunity to be listening to a P25 TRS with a Motorola radio, 436 and SDS100 a few months ago. I did not notice any appreciable delay in "timing" of reception.

There is a delay if there is an "analog to digital", but I think that's normal and nothing specific to what type of radio/scanners are involved.
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Old 05-16-2018, 11:18 PM
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I can attest that the 436/536, next to a Whistler or Motorola, will have an audio processing delay factor equivalent to placing two identical radios, one at a distance of 20 feet away. When trying to listen to 6-7 receivers at once, the added delay puts a real strain on the mental processes responsible for discerning information from the voice, which can be an issue.

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Old 05-17-2018, 5:50 AM
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I have also seen all the same brand and model radios at the same scene echo.
All Motorola's
All Kenwood's
P25 systems
DMR systems
NXDN systems
I have seen this at a SO with 3 DMR walkies APX's
I have seen this at a wreck 3 P25 APX8000's
I have seen this at a local site 3 NXDN NX5300's
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Old 05-17-2018, 6:31 AM
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Quote:
Originally Posted by Anderegg View Post
I can attest that the 436/536, next to a Whistler or Motorola, will have an audio processing delay factor equivalent to placing two identical radios, one at a distance of 20 feet away. When trying to listen to 6-7 receivers at once, the added delay puts a real strain on the mental processes responsible for discerning information from the voice, which can be an issue.
If you have 6-7 receivers all listening to the same transmission, you're always going to have variations in the timing of audio output even if they are all the same brand and model, due to buffering, and where the CPU happens to be in the processing loop when the transmission starts being received.

The real question is why do you have 6-7 radios listening to the same channel?
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Old 05-17-2018, 6:53 AM
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Not all hit the same channel, but certain talkgroups do. And I have never dealt with any buffering of live scanner audio, and the delay, if significant enough, make some audio transmissions unintelligible. Just look at the timing of human speech, throw in even just a 100-200ms delay, and you start loosing sylabal sync and such, it is a mess.

I use a main Motorola radio to "lock in" an active incident, but that same channel will still be spitting out of the scanner that alerted me to tune the Moto into it.

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Old 05-17-2018, 7:15 AM
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And I have never dealt with any buffering of live scanner audio, and the delay, if significant enough, make some audio transmissions unintelligible.
Wrong. All digital audio is buffered. Especially with TDMA, buffering is mandatory, or the audio would cut out 50% of the time. On the transmission side, audio is digitized, packaged into frames, and transmitted. In the receiver side, those frames are received, decoded, and converted back to audio. Typical time from mic to speaker is about 400ms. This is related to the frame size, and how much digital data you need to decode a segment of audio after error correction and decompression, etc.

I've noted audio timing variations between two DMR radios receiving the same transmission, as well as two scanners receiving the same digital transmission even though they were identical models running the same firmware. It's not a bug in the x36 series, it's just something inherent to digital radio.
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Old 05-17-2018, 7:22 AM
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I meant I have never heard a buffering variance between two identical scanners on non TDMA. I use the term DSP processing as a catch all for these things that delay the speaker output of the decoded received audio. Anyone know any links to an SDS100 next to a Whistler or Motorola on the same talkgroup?

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Old 05-17-2018, 7:27 AM
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We must really be running out of inane things to complain about or demand on the x36 scanners...
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Old 05-17-2018, 7:42 AM
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Haha, not a complaint or demand, it is just an important factor in my purchasing decision for 20 new Phase II scanners for my TV station. :-)

Paul
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Old 05-17-2018, 7:45 AM
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Quote:
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I meant I have never heard a buffering variance between two identical scanners on non TDMA.
I have, and so have others, with scanners and multiple brands of digital radios, on all the major digital formats. It's just part of live digital audio.
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Old 05-17-2018, 8:02 AM
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Audio can also be delayed on the same talkgroup if you try to monitor different sites due to network latency. I have heard delays using the same model of scanner parked on different sites.
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Old 05-17-2018, 11:38 AM
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I have 2 Digital TV's at the Fire Station of the same brand and make same tv channel 1 second delay in decoding they are one room apart and very annoying.
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